EDIT: Also looking for a list of all known species, especially if they have space travel technology.
SPACE TRAVEL:
Double-Helix - A race of arthropod-like aliens with double-helix-shaped spacecraft. They were first encoutnered in 2654 and contact was eventually made.
Firekkans - You already know these ones. The Firekkans seem to be just developing space capabilities when we meet them in Secret Missions II, but there are more impressive references later (they have their own fighters and a colony by the turn of the century).
Hari - Species of 'world eaters' with generational ships which were slaughtered by the Kilrathi. Survivors all comitted suicide.
Kilrathi - If you don't know these guys, you're in the wrong place.
Mantu - Race of aliens who fought a war with the Kilrathi that ended in a draw. Considered by the Kilrathi to be a grave threat, but actually a race of "insular explorers".
Nephilim - The insects from Wing Commander Prophecy.
Shata - Race wiped out by the Kilrathi.
Steltek - Precursor aliens from Privateer; still out there somewhere...
Terrans - That's you!
Utara - Race wiped out by the Kilrathi.
Varni - Republic of lizard men enslaved by the Kilrathi shortly before their first contact with Earth.
Wu - Race of elephant-sized aliens enslaved by the Kilrathi.
Yan - Race that fought Earth in the 24th century.
POSSIBLE SPACE TRAVEL:
Dolosians - Kilrathi slave race; focus of the 2654 Sivar-Eshrad ceremony.
Eyoka - Kilrathi conquest/likely slave race.
Gorth - Kilrathi conquest/likely slave race.
Hagarin - Tolwyn mentions having seen Hagarin at the Academy (in the 2630s).
Haggan - We see Haggan on the frontier in Action Stations. Possibly snake-like--the book mentions that one "slithers" up to Tolwyn and friends. (Which is interesting in and of itself, because you'd assume he meant to repeat the reference to Hagarins and got the word wrong... but the Hagarin bit is explicitly *not* an alien that looks like a lizard.)
Jarma - Lizard aliens seen trading on the frontier in Action Stations.
Ka - Kilrathi conquest/likely slave race.
Oasians - The super-peaceful aliens from the Recreation episode of Wing Commander Academy... sitting all pretty with their magic... sphere... and their... viking friend... what was I saying?
Sorn - Kilrathi conquest/likely slave race.
NO SPACE TRAVEL:
Dioscuri - Race of primitives the Kilrathi lend-lease old Dralthi to on Wing Commander Academy.
Mopokes - Also spelled Mopoks. These are the little red guys on Rostov III who help defeat the Kilrathi in the Rostov system cutscene in Wing Commander I.
